“Biosignatures Across Space and Time,” a joint conference of the Nordic Astrobiology Network and the University of Bergen’s Centre for Geobiology, was held in Bergen, Norway, 20 to 22 May 2014. More than 100 scientists from 19 countries gathered to discuss aspects of the origins, evolution, and potentially observable biomarkers of life on Earth and other worlds. Dozens of the more than 85 lecture and poster presentations focused on aspects of the detection, distribution, and characterization of carbon compounds in the Cosmos.
Day 1 was devoted to prebiotic molecular synthesis and the identification and characterization of atmospheres and organic molecules on distant planets. Xander Tielens (Leiden University, the Netherlands) presented the introductory lecture on “Biosignatures in astronomy and planetary science”—a survey of observational efforts to detect distant organic molecules. Subsequent talks focused on locating exoplanets, characterizing planetary atmospheres, and the remote sensing of biosignatures. The day’s final session considered mineralogical and organic biomarkers on Mars, with new data from the Mars Science Lander by Janice Bishop (SETI, USA) and Joseph Michalski (Natural History Museum, London, UK). That evening, DCO Executive Director Robert Hazen (Carnegie Institution, USA) presented the Horizon Public Lecture, “The Co-Evolution of the Geosphere and Biosphere,” which reviewed Earth’s changing near-surface environment, including its dynamic carbon cycle, through deep time.
The conference’s second day concentrated on near-surface environments of early Earth and other planets, focusing on factors that make planets habitable. Mark Sephton (Imperial College, UK) discussed “Organic matter in meteorites,” with an emphasis on their contributions to prebiotic carbon inventories on Earth. Talks by Anna Neubeck (Stockholm University, Sweden) and Hoi-Shan Chen (NASA Johnson Space Center, USA) elaborated on mechanisms of prebiotic molecular synthesis in asteroids and hydrothermal systems. The second session of the day shifted focus to early Earth. Martin Whitehouse (Stockholm University, Sweden) addressed the detection and origin of traces of possibly biotic carbon in Paleoarchean rocks from Isua and Akilia, Greenland. Victor Melezhik (Norwegian Geological Survey), who described unusual carbon-bearing lithologies recovered in drill cores of Paleoproterozoic rocks by the Fennoscandian Arctic Russia—Drilling Early Earth Project (FAR-DEEP; http://www.icdp-online.org), explored how carbon-bearing phases can reveal details of atmospheric composition during and following Earth’s Great Oxidation Event ~2.4 billion years ago.
Bergen panoramic photograph taken from Fløyen mountain
Following a memorable lunch of traditional Bergen fish soup, the subject shifted to near-surface planetary environments and biosignatures. Frances Westall (Centre de Biophysique Moléculaire CNRS, France) discussed varied scales, from nano to macro, of “Biosignatures for Mars: Lessons from early Earth.” Conference organizers Eugene Grosch and Nicola McLoughlin (University of Bergen, Norway) considered “Candidate biosignatures and subsurface alteration environments on early Earth and Mars,” with new data from carbonate-bearing rocks from the Barberton greenstone belt, South Africa. Everett Gibson (NASA Johnson Space Center, USA) reviewed an ongoing controversy related to purported evidence for martian life, including carbonate minerals, magnetite crystals, and distinctive textures, found in Mars meteorites. The day’s final session examined consequences of large impacts on rocks and life. Vivi Vajda (Lund University, Sweden) considered new data regarding plant extinctions at the Cretaceous-Paleogene boundary and subsequent rapid evolution following the Chicxulub impact. Magnus Ivarsson (Nordic Center for Earth Evolution, Stockholm, Sweden) described a fossilized deep microbial ecosystem from hydrothermal zones associated with the much smaller (4 km diameter) Lockne impact structure in Sweden. Kalle Kirsimae (University of Tartu, Estonia) reported on hydrothermal carbonate production in hydrothermal zones associated with the Haughton impact structure in Arctic Canada. These results suggest that impacts may have played a significant role in the deep carbon cycle of early Earth.
The meeting’s third day featured a dozen talks on the deep biosphere, with sessions on serpentinization, sub-seafloor environments, extremophiles, and microbial biosignatures. John Parkes (Cardiff University, UK) set the tone by reviewing “Microbial life in the deep biosphere,” with an entertaining history of discoveries of deep life, and a survey of recent results on the extent of the deep biosphere (including many contributions by DCO scientists). Subsequent talks on “Linking abundance of prokaryotes and geochemical parameters in deep-sea marine sediments” (Stephan Jørgeson, University of Bergen), “Water-rock interactions and microbial life within the ocean crust” (Wolfgang Bach, University of Bremen, Germany), and “Formation of H2 during low-T alteration of ultramafic rocks” (Ingeborg Okland, University of Bergen) revealed the rapid pace of discovery in the study of deep microbial life.
Geochemical properties and microbial life of hydrothermal systems provided the focus of the day’s second session. Chris German (Woods Hole Oceanographic Institute, USA) considered hydrothermal systems as “Oases for life on Earth and beyond”—a theme echoed by subsequent speakers. John Parnell (University of Aberdeen, Scotland) examined preservation of ancient hydrothermal ecosystems in carbonate and sulfide minerals, and speculated that, prior to the rise of the terrestrial biosphere, subsurface microbes represented most of Earth’s biomass.
The conference concluded with a session on biosignatures that might be preserved from deep microbial communities, both in ancient Earth rocks and on Mars. Kathleen Campbell (University of Auckland, New Zealand) provided an especially vivid picture of the preservation of biosignatures in diverse hydrothermal silicified zones from New Zealand and Patagonia. Speakers invoked such diverse lithologies as microbial carbonates (Fernando Gomez, Universidad Nacional de Cordoba, Argentina), alkaline lake sediments (Lise Øvreås, University of Bergen), and sulfates (Ida Helena Stein, University of Bergen) in their search for preserved signs of deep life.
The conference schedule, contact information for attendees, and abstracts are archived at: http://www.nordicastrobiology.net/Biosignatures2014
Submitted by R. M. Hazen, 22 May 2014.